This invention relates to a spinal monitor apparatus and method. This invention has particular application to a spinal monitor apparatus and method for use in diagnosis and treatment of lumbar dysfunction and training desirable postural habit and hereinafter this invention will be described in terms of this application. However, it is envisaged that a spinal monitor apparatus and method in accordance with the present invention will find other applications such as on other portions of the spine, or in other applications such as encouraging good lifting practices.
The prevention and treatment of back problems including those caused by poor posture and poor work practices such as unsafe lifting practices is important economically and in terms of quality of life. The underlying causes of poor posture for example are many, and include acquired habits and injury. Treatment may include surgical intervention or physiotherapy, and the use of prostheses such as back braces or corsets. The palliative apparatus are also restrictive, uncomfortable and carry negative social implications. Further, restriction by these means may interfere with nutrition of the intervertebral discs which is usually enhanced or encouraged by flexion in the normal range.
A further problem resides in the fact that the inter-vertebral discs have a negligible nerve supply. Therefore, under normal circumstances, they feel no pain. When a person habitually assumes incorrect posture (whether sitting, standing or lifting) damage is being done unwittingly because there is no pain to act as a warning of impending and cumulative damage.
The disadvantages of the traditional palliative measures, the limitations of physiotherapeutic treatment and the drastic nature of surgical intervention, have led to development of several non-invasive posture training aids. One of the characteristics of the human spine which distinguishes it from the spine of most other vertebrates is the sinuous form, presenting a substantially concave lumbar region, transforming into a substantially convex dorsal presentation in the thoracic region. A key element in maintenance of good posture and ameliorating or preventing injury is the maintenance of the appropriate lumbar curvature or lordosis. Several prior art apparatus-have been suggested for this purpose.
United Kingdom Patent No. GB-2205039 (Williams) discloses an apparatus for monitoring spinal flexion and including a casing adapted to be supported in the region of the 12th thoracic (or dorsal) vertebra and forming a first reference point and an elongate monitoring member in the form of a resilient extension extending from the casing to bear on the spine in the region of the first sacral vertebra, thus forming a second reference point. In use, the apparatus emits a noise or vibration when the spatial relationship between the second reference point, resiliently biased toward the spine, and the casing, approaches that which would be induced when the reference points correspond to a selected loss of lumbar lordosis.
A disadvantage of the apparatus disclosed in the Williams reference is that the two reference points utilized do not measure the loss of lordosis as such. The apparatus merely monitors the spatial relationship between the two reference points. The disclosed apparatus does not monitor and respond to changes in curvature of the spine directly or indirectly. Where the Williams apparatus does indicate loss of lumbar lordosis, it does so incidentally. With reference to the example disclosed at page 3, line 5 through to 7 of the Williams reference, there is reference to touching the knees and bending over, clearly flexion type movement not directly dependent upon a change occurring in the curvature of a particular portion of the spine.
The Williams apparatus would not detect flattening of the lumbar curve if the user is sitting upright in a chair but still slumping in the lumbar spinal region.
The lumbar curvature may be lost without inclining. This may be demonstrated by the observation that a person may bend forward at the hip joint without flattening the lumbar curvature.
In one aspect the present invention resides broadly in a method for the prevention and treatment of posture deficiencies including the steps of:
monitoring a selected portion of a spine for functions of curvature;
producing a signal corresponding to said monitored curvature, and
using said signal to provide an indication of said curvature.
The function of curvature may be selected from the displacement of curvature, rate of change or velocity of curvature, or acceleration of curvature change.
The monitoring of the function of curvature may be continuous or intermittent monitoring. The type of signal generated by the signal means may take any form determined by the choice of monitoring means and signal means, as well as the type of indication of curvature required. The functions of curvature expressed by the indicator means may for example represent displacement of curvature, or alternatively some other function such as rate of change of curvature or accelerations of that rate.
In a further aspect this invention resides broadly in apparatus for the prevention and treatment of posture deficiencies including:
monitoring means adapted to directly or indirectly monitor the curvature of a portion of a spine; and
signal means responsive to said monitoring means and adapted to generate a signal indicative of said curvature.
The portion of the spine may be any portion for which conditions of adverse curvature are relevant to matters of prevention, treatment, training or maintainence of posture. Examples include the lumbar, thoracic and cervical spine. The curvature may be in the dorsal, sagittal or any other plane.
The monitoring means may be adapted to monitor the curvature of the selected portion of the spine as a continuous smooth curve or alternatively may monitor the curvature by reference to discrete positions on the spine.
However, where the monitoring of discrete positions on the spine is used, the monitoring means must monitor the actual curvature of the spine directly or indirectly, rather than from inference. Accordingly, where the monitoring means monitors the spatial relationship between discrete selected locations on the spine, there must be at least three of the selected locations to provide a first approximation of the curvature.
The monitoring means may be adapted to monitor curvature and provide a signal dependent on the angular displacement between adjacent monitor elements of a plurality of monitor elements attached to or in contact with the selected plurality of selected spinal locations. Alternatively, the monitoring means may include a unitary body member secured to the selected spinal region and including internal signal generating means responsive to the direct correspondence between the body member and the spinal curve to which it is attached.
The monitoring means may advantageously include a flexible body member adapted to conform in use to the lumbar portion of the wearer""s spine, and securing means. The securing means may also take any form consistent with the function of maintaining the body member in position on the wearer. For example, the securing means may comprise one or more of adhesive pads or tape members, straps or any other suitable means. The monitoring means may for example comprise an elastomeric housing having a surface adapted to engage the skin of the user by way of an adhesive layer. For example, the adhesive may comprise a medical grade hypoallergenic adhesive. Preferably the securing means, and indeed the body member and securing means in assembly, are such that they are unobtrusive to avoid embarrassment of the wearer in use. In certain embodiments of the present invention, the securing means may adjustably mount the body member to provide an element of fine-tuning to the positioning the body member relative to the part to be monitored.
The signal means may comprise electromagnetic, electronic, optical, electromechanical, pneumatic or mechanical signal means. Preferably, the monitoring means and signal means are configured such that the mechanical reaction of the apparatus to movement of the spine of the user is minimized such that the user""s awareness of the action of the apparatus is minimized. Accordingly, in the case of discrete monitoring elements, the interrelation between the adjacent elements is preferably monitored by optical or electronic means and the signal generated is optical, electronic via an optical coupler, or electronic as appropriate.
The signal means may only provide a signal in response to the, for example, curvature of the spine when it exceeds certain predetermined limits. Accordingly, the signal means may be selected from a wide array of signal means including pressure, temperature, conductivity or proximity signal means. However, it is preferred that the monitoring means provide a continuous output across a range of positions of the monitoring means.
The signal means may include magnetic signal means such as reed switches or inductance devices and accordingly the signal means may include a body mounted portion acting in conjunction with, for example, a magnetic component attached to the wearer. Alternatively, the signal means may comprise an elongate flexible strip of metal or plastic embedded in the flexible body member and having one end adapted to interact with a transducer selected to output a signal corresponding to the curvature. In order that the signal means faithfully reflects the curvature of the monitoring means and thus the spine of the user, there may be provided signal means comprising a metal strip embedded in the elastomeric body of the monitoring means and cantilevered from a relatively rigid portion thereof. A pair of strain gauge transducers may be provided on the opposed flat surfaces of the strip, which may be said to have a ventral surface and a dorsal surface. Thus a differential signal may be generated which corresponds to the curvature of the strip and hence the curvature of the user""s spine.
The signal generated by the signal means may interface with indicator means which may include any one or more of vibratory stimuli, audio stimuli, electrical stimuli or a visual indication such as screen based outputs or indication lights. For example, the indicating means may comprise an aversive indication of an adverse static or dynamic curvature and be of an unpleasant or irritating nature to reinforce the maintenance of good posture and to this end it is preferred to utilize a method which involves vibro-tactile stimulus of sub-audible frequency. Alternatively, the indicator means may serve to signal the wearer of the condition such that positive reinforcement of, for example, poor posture habits may be attained. Where the user is receiving a condition responsive indication of adverse posture, this stimulus may be applied immediately or after a selected delay.
Of course, the apparatus may be so configured that both condition responsive and timed stimuli are supplied to the wearer, to indicate poor posture and to stimulate the wearer periodically for voluntary postural variety respectively. The timed stimuli of such apparatus may be user programmable to act as an unobtrusive alarm or reminder system. The timed stimulus may take the form of a mild electric shock, thermal indication, visual indication or soft, audible indication, or any other suitable indication. However, it is preferred that the indicator means again include means capable of generating a vibration to which the wearer""s tactile sense can respond, the vibration preferably being of sub-audible frequency and/or volume such that the vibration cannot be detected by others.
The indicator means may be deactivatable to permit gathering of baseline data on the curvature function of the patient.
The signal means may output to indicator means that may be selected from means of recording condition status on a continuous, intermittent or condition responsive basis. For example, for diagnosis and treatment by a health care professional, there may be associated with the apparatus a data terminal or console unit. The console unit may be adapted to receive data comprising a processed version of the signal from the apparatus in real time or batch mode. Alternatively the console may deal with raw signal. The data or signal may be transmitted to the console by cable and/or wirelessly. In a wireless example, a coil may be embedded in the apparatus and adapted to receive and transmit the modulated signal from the signal means via appropriate circuitry.
A power supply may be provided to power the circuitry associated with the preferred apparatus. The power supply may be integral with the body member or securing means, or may be located apart therefrom and connected by suitable wires or the like, such that the power supply may be carried in a pocket. The power supply preferably takes the form of a wireless power supply. For example the power supply may comprise an inductive coil within the monitoring means body and adapted charge rechargeable batteries therein. The inductive charging may be facilitated by a cradle mount for the monitoring means body having an electric field generator in close proximity to the inductive coil when the monitoring means body is so mounted. The inductive coil may perform the alternating duties of radiating member for wireless data transfer and inductive charging coil for maintenance of the batteries.
When used in a rehabilitatory role or posture training role, the console and/or monitor apparatus may advantageously be provided data collection such as with a counter, time base record or the like adapted to record the number and timing of stimuli applied to the wearer by the reacting means. The console may form part of or be connectable to a PC for data processing and statistical analysis to assist in diagnosis and therapeutic design.
The purpose of the preferred embodiments of the present apparatus and method is to provide a method of monitoring in real time, and presenting feedback to the user, data relating to their posture, as measured by the curvature profile of their lower spine relative to an ideal or reference posture. This may be undertaken in the static situation, typically with the user in a sitting position, or in the dynamic situation, with the user undertaking activities ranging from normal day-to-day tasks through to heavy lifting or exercise conditions.
In operation, the preferred apparatus performs a number of specific functions of benefit to the user, including:
(a) postural training, wherein warning the user that their posture has deviated from the ideal reference by a pre-set degree over a pre-set period of time, makes the user aware of the need for postural correction to avoid long-term spinal damage, or the aggravation of a pre-existing condition. Postural training also conditions the postural support muscles and the brain""s motor control of these muscles;
(b) postural monitoring, wherein recording over a period of time the user""s posture relative to the ideal reference posture and making the recorded data available for analysis by trained personnel, the system allows user behavior which may threaten the health of the spine to be detected and corrected. Faulty equipment such as seating or workstations the use of which may threaten the health of the spine may also be detected and replaced of reconfigured; and/or
(c) preventative training, wherein the knowledge that spinal conditions can result from and be aggravated by persistent periods of postural monotony is used in monitoring activity and warning the user of periods of postural monotony which exceed a predetermined elapsed time, such that a certain minimum level of postural variety can be achieved, thereby minimising the risk of this phenomenon.
To achieve these ends the apparatus may be operated in various modes. For example, there may be defined a sitting mode and a lifting mode: These may be pre-set combinations of parameters. The sensitivity of the apparatus and the regimes applies may be variable. For example there may be 3 levels of sensitivity in the sitting mode and in the lifting mode. The user may be able to adjust the underlying values behind the sensitivities (i.e. the levels) but when the product is shipped, the level 1 may be the xe2x80x98easiestxe2x80x99 level (i.e. sensitivity), level 2 may be intermediate and level 3 may be advanced. In other words, level 1 may allow the greatest range of movement before the limits are transgressed, and level 3 may be the smallest (and therefore most difficult) range.
The apparatus may be provided with varying access levels such as normal user access, researcher access, and developer access. Normal user access may be the product""s normal access level. Researcher access may allow the user to change the underlying values behind the preset levels whilst absolute values are not revealedxe2x80x94only relative values from the neutral (central) posture. Developer access also allows the underlying values to be changed, but absolute values are displayed, not relative values.
The range of allowable movement within any Level (sensitivity) is not necessarily symmetrical in each direction in the sagittal plane. For example, when the user begins a posture training Session (whereby they receive feedback when their posture goes outside of the desired range), they assume the ideal xe2x80x98neutralxe2x80x99 spinal posture and then press the train key on the console (or it could be on the sensor itself). Pressing the train key enters/logs the neutral posture, around which the allowable range will be calculated. The amount of movement allowed in the flexion (forward-bending) direction is usually more than is allowed in the extension (lumbar-arching) direction. The point is that the range of allowable flexion and extension is not necessarily symmetrical either side of the neutral spinal position. Also, these flexion and extension limits can be adjusted either semi-automatically by choosing a different sensitivity level or manually via the researcher access function.
Preferably, the apparatus and method is not used to provide stringent posture training for many hours on end. A most stringent form of training provided by the apparatus is preferably set in the apparatus, where the user must stay within the desired posture range if a posture transgression is to be avoided. Such a posture training session may begin by (a) the wearer assuming the ideal neutral posture (be that in sitting or standing), and then (b) pressing the train key. Pressing the train key may for example do three things: (1) log the neutral posture for that posture training session, (2) log the date and start time of the posture training session, and (3) begin the countdown timer that will automatically end the posture training session after the allotted time. This may be 5 minutes, 15 minutes, 60 minutes or any period desiredxe2x80x94i.e. it is user-defined and variable. This auto-dosage function may help avoid over-training with the apparatus.
The apparatus and method of the present invention lends itself to three distinctly different forms of training: (1) Static posture maintenance, (2) Avoidance of end-range postures, and (3) Avoidance of spinal immobility. Static posture maintenance refers to the posture training sessions whereby the user tries to stay within the prescribed posture range for the duration of the posture training session. During posture training sessions the xe2x80x9cout of ideal posture rangexe2x80x9d feedback is emitted immediately or with only a very small delay (in the order of a few seconds).
Avoidance of end-range postures (e.g. slumping whereby the person""s spinal joints xe2x80x98hangxe2x80x99 on their ligaments, thus stretching and damaging them and therefore contributing to the instability and vulnerability of their spine) also involves notifying the wearer when their posture is outside of the desired range, but the feedback is not immediatexe2x80x94it is delayed in the order of minutes; e.g. 1 to 15 minutes. This delayed feedback does not condition the muscles"" motor control ability as does more immediate feedback. Instead, the purpose of the delayed feedback is simply to remind the wearer to get out of end-range postures after a number of consecutive minutes of being outside of the ideal posture range. This aims to develop the habit of returning to the neutral range momentarily on a frequent basis throughout the day.
Avoidance of spinal immobility refers to the time-based xe2x80x98stretch breakxe2x80x99 reminders. These have a different objective to (2) above. Instead of encouraging the user to briefly return to the neutral range, the stretch break reminders encourage the user to gently move through their full range of motion in all planes-sagittal, lateral and torsional.